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Greek Small Delta:   δ   delta
Integral sign:       ∫   int 

Infinity symbol:     ∞   infin
Intersection cap:    ∩   cap 
Element of:          ∈   isin
Partial differntial: ∂   part
There exists:        ∃   exist
For all:             ∀   forall
Follows (r arrow):   ⇒   rArr
Follows (l arrow):   ⇐   lArr
Equivalent:          ⇔   hArr
Empty set:           ∅   empty
Nubla operator:      &nubla;   nubla
Not element of:      ∉   notin
Contains a member:   ∋   ni
Product sign:        ∏   prod
Summation sign:      ∑   sum
Set's union:         ∪   cup
Tilde:               ∼   sim
Almost equal:        ≈   asymp
Not equal to:        ≠   ne
Identical to:        ≡   equiv
Less or equal:       ≤   le
Greater or equal:    ≥   ge 
Superset of:         ⊃   sup
Not a subset of:     ⊄   nsub
Direct sum:          ⊕   oplus
Direct product:      ⊗   otimes
Orthogonal to:       ⊥   perp
Subset of            ⊂   sub 




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This characters is a part of HTML 4.01 specification.